This is the third year of a three-year investigation of Bragg diffraction as a practical imaging technique for medical diagnosis. During the past year we modified and improved the low-frequency imaging system previously constructed by providing a better technique for isolating the acousto-optic interaction region to keep the water in that region pure and to minimize streaming and turbulence, by developing a castor-oil sound absorber and fitting it into the camera cell to reduce reflections and eliminate ringing and speckle, by designing and building a spherical acoustic lens for resolution improvement and by building a Pohlman cell for possible use with the Bragg system as an alternative to the acoustic lens. In addition, we applied digital image-enhancement techniques to the images obtained and performed preliminary experiments involving pulsed operation to provide range gating for reflection-mode imaging. We also completed a theoretical analysis in which the ultimate sensitivities of three competing real-time acoustic imaging techniques were compared. Some of our immediate goals for the coming year include: 1. Continued experimentation for maximizing the effect of the system modifications made last year and described above. 2. Continued development of digital techniques for image enhancement. 3. Application of the information obtained from carrying out steps 1 and 2 in constructing a practical system for medical diagnosis.